Add support for github enterprise

[philipcraig]

Hi, could this please be extended to support github enterprise setups?

[fiatjaf]

I don't know how does a GitHub Enterprise look and what would it take, never used one.
I imagine you just have to change some URLs, right?
How does the API work for GitHub Enterprise? We use GitHub API to fetch repository trees.

[philipcraig]

It's exactly the same API, just some URLs change, as you said. Whereever github.com is hard-coded, it needs to be replaced with the github enterprise's URL

[fiatjaf]

What is that URL?

[AlexWayfer]

What is that URL?

I guess, it's a custom URL, especially with self-hosted version of GitHub. So, I think, base URL (domain) should be configurable in the extension.

[fiatjaf]

But the base URL should change depending on which repository the person is visiting.
So if I'm in https://my.custom.github.url/myuser/myrepo what is the API URL?
Or does a person who uses GitHub Enterprise also browses public repositories through that always?

[philipcraig]

Hi, here is an example curl session to an enterprise server. It shows basic use of GitHub API.

It shows that the API URL is the server's hostname (this needs to be configurable as it's different for every Enterprise git server). Also, for most (all?) Enterprise git servers, nothing useful happens unless you authenticate with your username and a Personal Access Token, so there needs to be a way to provide those also.

curl -i -u gitusername:gitpersonalaccesstoken https://enterprise.gitserver.tld/api/v3/zen

HTTP/1.1 200 OK
Server: github.com
Date: Fri, 10 Jul 2020 20:12:09 GMT
Content-Type: text/plain;charset=utf-8
Content-Length: 26
Status: 200 OK
X-RateLimit-Limit: 30000
X-RateLimit-Remaining: 29970
X-RateLimit-Reset: 1594414252
Access-Control-Expose-Headers: ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type
Access-Control-Allow-Origin: *
X-GitHub-Request-Id: 98ae8059-d8bb-46be-a5fb-e3ec8d94467e
Strict-Transport-Security: max-age=31536000; includeSubdomains
X-Frame-Options: deny
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Referrer-Policy: origin-when-cross-origin, strict-origin-when-cross-origin
Content-Security-Policy: default-src 'none'
X-Runtime-rack: 0.029544

Favor focus over features.

The gory details are all here:

https://docs.github.com/en/enterprise/2.21/user/rest/guides/getting-started-with-the-rest-api

and you could compare with the public GitHub version of the same thing by contrasting the above with the page here:

https://docs.github.com/en/rest/guides/getting-started-with-the-rest-api

Essentially, URLs in this extension that are written beginning as http(s)://api.github.com/command would need to become a configurable hostname, in the form: http(s)://enterprise.gitserver.tld/api/v3/command